Atrial fibrillation (AF), once thought of as a benign condition affecting a relatively small patient population, has recently been found to be a major contributor to stroke and congestive heart failure (CHF), and is expected to afflict a much larger patient pool, particularly as the population ages, making AF one of the largest unmet cardiovascular clinical opportunities. The only current cure for AF is a traumatic, rarely performed surgical procedure. Palliative treatments are limited to drug regimens that are often ineffective and can produce serious side effects; or electrophysiology and cardiac rhythm management procedures that are only used for a relatively small number of patients. The size of the AF patient market and the recent discovery that AF is a precursor to stroke and CHF have elevated the condition in importance to product companies, making it one of the most competitive areas for the next generation of cardiovascular devices, and attracting interest from all the major cardiology companies, as well as many start-ups. AtriCure is developing novel technology that for the first time enables surgeons to ensure they are producing lesions that are transmural, meaning they completely penetrate the cardiac tissue. Transmural lesions have been shown to provide the only effective means of curing AF. The company's first-mover advantage puts it ahead of the pack, at least for now. AtriCure's challenge is to expand the application of its technology to avoid being marginalized when the inevitable rush of big and small players enter the market.